qapi: Fix crash on redefinition with a different condition

QAPISchema._make_implicit_object_type() asserts that when an implicit
object type is used multiple times, @ifcond is the same for all uses.
It will be for legitimate uses, i.e. simple union branch wrapper
types.  A comment explains this.

The assertion fails when a command or event is redefined with a
different condition.  The redefinition is an error, but it's flagged
only later.

Fixing the assertion would complicate matters further.  Not
worthwhile, drop it instead.  We really need to get rid of simple
unions.

Tweak test case redefined-event to cover redefinition with a different
condition.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210806120510.2367124-1-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index d1d27ff7ee8f7d6aa40f75eb002cfc443eb2a67f..a4ce3972a4eb21db18e3efca3b58bdb712e82649 100644 (file)
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -997,18 +997,18 @@ class QAPISchema:
         name = 'q_obj_%s-%s' % (name, role)
         typ = self.lookup_entity(name, QAPISchemaObjectType)
         if typ:
-            # The implicit object type has multiple users.  This can
-            # happen only for simple unions' implicit wrapper types.
-            # Its ifcond should be the disjunction of its user's
-            # ifconds.  Not implemented.  Instead, we always pass the
-            # wrapped type's ifcond, which is trivially the same for all
-            # users.  It's also necessary for the wrapper to compile.
-            # But it's not tight: the disjunction need not imply it.  We
-            # may end up compiling useless wrapper types.
+            # The implicit object type has multiple users.  This is
+            # either a duplicate definition (which will be flagged
+            # later), or an implicit wrapper type used for multiple
+            # simple unions.  In the latter case, ifcond should be the
+            # disjunction of its user's ifconds.  Not implemented.
+            # Instead, we always pass the wrapped type's ifcond, which
+            # is trivially the same for all users.  It's also
+            # necessary for the wrapper to compile.  But it's not
+            # tight: the disjunction need not imply it.  We may end up
+            # compiling useless wrapper types.
             # TODO kill simple unions or implement the disjunction
-
-            # pylint: disable=protected-access
-            assert (ifcond or []) == typ._ifcond
+            pass
         else:
             self._def_entity(QAPISchemaObjectType(
                 name, info, None, ifcond, None, None, members, None))

diff --git a/tests/qapi-schema/redefined-event.json b/tests/qapi-schema/redefined-event.json
index 7717e91c18c4b44f33211e2a2696da2d921e1b1e..09eff1841288a90a0d66263c87ba19e4ee42a857 100644 (file)
--- a/tests/qapi-schema/redefined-event.json
+++ b/tests/qapi-schema/redefined-event.json
@@ -1,3 +1,3 @@
 # we reject duplicate events
 { 'event': 'EVENT_A', 'data': { 'myint': 'int' } }
-{ 'event': 'EVENT_A', 'data': { 'myint': 'int' } }
+{ 'event': 'EVENT_A', 'data': { 'myint': 'int' }, 'if': 'defined(FOO)' }